The present invention relates generally to x-ray tube components and systems. More particularly, the present invention relates to an apparatus for absorbing kinetic energy within an x-ray tube before absorption by an x-ray tube housing.
An x-ray system typically includes an x-ray tube that is used in the imaging process for the generation of x-rays. The x-ray tube generates x-rays across a vacuum gap between a cathode and a rotating anode. In order to generate the x-rays, a large voltage potential is created across the vacuum gap, which allows electrons to be emitted, in the form of an electron beam. The electron beam is emitted from the cathode to a target on the anode. The target is often in the form of a cap that is brazed onto the anode and is formed of a graphite material.
In releasing of the electrons, a filament contained within the cathode is heated to incandescence by passing an electric current therein. The electrons are accelerated by the high voltage potential and impinge on the target, where they are abruptly slowed down to emit x-rays. The high voltage potential produces a large amount of heat within the x-ray tube, especially within the anode.
The cathode and the anode reside within a vacuum vessel, which is sometimes referred to as an insert or frame. The frame is typically enclosed in a housing filled with circulating, cooling fluid, such as a dielectric oil. The cooling fluid often serves two purposes: cooling the vacuum vessel, and providing high voltage insulation between the anode and the cathode.
Over time, through use of the x-ray system and as a result of material or manufacturing imperfections in the target, material fragments of the target can break away or separate from the anode. The material fragments can be released radially from the target cap and subsequently collide with the frame.
Kinetic energy of the target fragments and the abrupt collision of the fragments with the frame can cause generation of energy waves in the cooling fluid. The cooling fluid absorbs some of the kinetic energy. The remaining kinetic energy is transmitted to the housing, where a substantial portion of the remaining energy is absorbed. The strength of the remaining kinetic energy can be sufficient to crack the housing, allowing oil to leak therethrough. Leakage of the oil can result in the malfunctioning of the x-ray tube. Also, the oil may come in contact with and negatively effect performance of other sensitive x-ray system equipment. The oil may even be undesirably released on a patient being examined.
Thus, there exists a need for an apparatus that minimizes the transfer of kinetic energy, generated from the separation of material fragments of an x-ray tube rotating target, to an x-ray tube housing that is capable of withstanding the environment within an x-ray tube.